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Stellar Populations of Kinematically Decoupled Cores in E/S0 Galaxies

Published online by Cambridge University Press:  01 August 2006

Richard M. McDermid
Affiliation:
Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands email: [email protected]
Eric Emsellem
Affiliation:
Université de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles André, F-69230 Saint-Genis Laval; CNRS, UMR 5574; ENS de Lyon, France
Kristen L. Shapiro
Affiliation:
UC Berkeley Department of Astronomy, Berkeley, CA 94720, USA
Roland Bacon
Affiliation:
Université de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles André, F-69230 Saint-Genis Laval; CNRS, UMR 5574; ENS de Lyon, France
Martin Bureau
Affiliation:
Denys Wilkinson Building, University of Oxford, Keble Road, Oxford, United Kingdom
Michele Cappellari
Affiliation:
Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands email: [email protected] Denys Wilkinson Building, University of Oxford, Keble Road, Oxford, United Kingdom
Roger L. Davies
Affiliation:
Denys Wilkinson Building, University of Oxford, Keble Road, Oxford, United Kingdom
Tim de Zeeuw
Affiliation:
Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands email: [email protected]
Jesús Falcón-Barroso
Affiliation:
Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands email: [email protected] European Space and Technology Centre (ESTEC), Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands
Davor Krajnović
Affiliation:
Denys Wilkinson Building, University of Oxford, Keble Road, Oxford, United Kingdom
Harald Kuntschner
Affiliation:
Space Telescope European Coordinating Facility, European Southern Observatory, Karl-Schwarzschild-Str 2, 85748 Garching, Germany
Reynier F. Peletier
Affiliation:
Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands
Marc Sarzi
Affiliation:
Centre for Astrophysics Research, Science & Technology Research Institute, University of Hertfordshire, Hatfield, United Kingdom
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Abstract

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In this poster contribution, we present results from high spatial resolution integral-field spectroscopy of elliptical (E) and lenticular (S0) galaxies from the SAURON representative survey, obtained with the OASIS and GMOS spectrographs. These seeing-limited observations explore the central ∼10''10″ (typically one kiloparsec diameter) regions of these galaxies using a spatial sampling four times higher than SAURON (0″27 vs. 0″94 spatial elements), resulting in almost a factor of two improvement in the median PSF. These data allow accurate study of the central regions to complement the large-scale view provided by SAURON. We derive the stellar and gas kinematics, stellar absorption-line strengths and nebular emission-line strengths for our sample, and derive maps of the luminosity-weighted stellar age, metallicity and abundance ratio via stellar population models. From these data we find a wealth of structures either not seen or poorly resolved in the SAURON data, including a number of kinematically-decoupled cores (KDCs) in the centres of some galaxies. We compare the intrinsic size and luminosity-weighted stellar age of all the visible KDCs in the full SAURON sample, and find two types of components: kiloparsec-scale KDCs, which are older than 8 Gyr, and are found in galaxies with little net rotation; and compact KDCs, which have intrinsic diameters of less than a few hundred parsec, show a range of stellar ages from 0.5 - 15 Gyr (with 5/6 younger than 5 Gyr), are found exclusively in fast-rotating galaxies, and are close to counter-rotating around the same axis as their host. Of the 7 galaxies in the SAURON sample with integrated luminosity-weighted ages less than 5 Gyr, 5 show such compact KDCs, suggesting a link between counter-rotation and recent star-formation. We show that this may be partly due to a combination of small sample size at young ages, and an observational bias, since young KDCs are easier to detect than their older and/or co-rot ating counterparts.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007